A new study examining women’s perceptions of penis size has been making the rounds in the media lately with headlines ranging from “Science Proves Women Like Men with Bigger Penises,” to “This Just In: Women Prefer Well-Endowed Men,” to “Science Proves Women Love a Big ‘Ol D.” Based upon these and dozens of other international headlines, one might reasonably conclude that the age-old question “Does size really matter?” has been settled once and for all. So women who are attracted to men are looking for guys with humongous penises because a bigger penis makes for better sex, right? Not so fast. The reality is that these headlines don't tell the whole story, and this study says nothing about whether penis size affects female sexual pleasure.

The new study, published in the Proceedings of the National Academy of Sciences, sampled 105 Australian female college students, all of whom either identified as heterosexual or said they were exclusively attracted to men [1]. Each participant was shown a set of 53 videos, with each video featuring a different computer-generated image of a male figure. Each video was 4 seconds long and featured a life-size male figure rotating 30 degrees each direction so that participants could fully appreciate all of the curves and contours of his body and member. While I commend the authors for trying to make the images realistic, they ended up looking a little on the alien side to me—kind of like Doctor Manhattan, if you’ve ever seen the movie Watchmen. So, keep in mind that we're not talking about real men or real penises in this study, and that has definite implications for the kinds of conclusions we can draw.

Each figure varied in height, body shape, and penis size. In manipulating penis “size,” length and girth (i.e., width) covaried, meaning that bigger penises were both longer and wider—so, this study does not address whether length or width is more important. After viewing each video, participants rated how attractive the computerized man was on a scale ranging from 1 (not at all attractive) to 7 (very attractive).

Results indicated that height, penis size, and shoulder-to-hip ratio were positively correlated with judgments of attractiveness. In other words, the figures were deemed more attractive to the extent that they depicted a man who was taller, had a larger penis, and had shoulders that were broader than his hips (i.e., a V-shaped torso). Shoulder-to-hip ratio was, by far, the feature most strongly linked to perceived attractiveness—height and penis size generally mattered less, with one exception: among taller men, penis size was more important to ratings of attractiveness (i.e., tall men seemed to have more to prove).

However, it is important to note that the association between penis size and attractiveness was non-linear, meaning that size only produced big gains in attractiveness to a certain point. This is where many of the media reports got it wrong. Specifically, the increase in attractiveness started to decline once flaccid length reached 7.6 centimeters (about 3 inches)--adding more size beyond that produced much smaller gains in attractiveness, meaning that women weren't distinguishing as much between penises once they reached a certain minimum size. For the record, research suggests that 3 inches is actually a little less than the average flaccid penis length [2], which means this study tells us that women prefer average-sized men, and being bigger than that does not necessarily produce meaningful gains in attractiveness. Thus, “well-endowed” men with “big ‘ol Ds” may be ever-so-slightly more attractive on paper, but they're really not much different from guys with average penises. Another way of saying this is that while there may be a statistically significant difference, it's not practically significant.

It is also important to note that this study only asked women to rate attractiveness of the male figures. Attractiveness tells us nothing about whether size affects female pleasure. The reality is that most women report that bigger penises do not necessarily increase their likelihood of reaching orgasm. There are certainly some women who enjoy larger sizes, and no one is disputing that—everyone has different sexual preferences. But in general, most heterosexual women report that penis size does not have a huge effect on whether they climax during sex.

Another limitation of this study is that the researchers only showed flaccid penises, and flaccid penis size is not necessarily a good predictor of erect size. In other words, some guys are “growers” and others are “showers.” Also, how often are women really judging how attractive a man is based upon his flaccid size? For centuries, the penis has been hidden away by clothing, so there are very few times in the modern world in which a woman might judge how attractive a man is based upon the size of his flaccid penis (unless he happens to be wearing Lulu Lemon yoga pants and/or goes by the name of Jon Hamm). In reality, when women judge male attractiveness, personality counts for more than physical appearance [3]. However, because this study didn't take personality into account, we don't know to what extent penis size even matters. If penis size and body shape are the only information you have to go on, of course you'll use them in making judgments of attractiveness--but when you have more information (e.g., personality) like you do in the real world, flaccid penis size may matter less, and potentially not at all.

And, of course, this study only looked at the attractiveness judgments of about 100 young Australian women who were mostly White. Thus, it is disingenuous to try and say that these results tell us something about how ALL women feel about penises (or more precisely, computer-generated images of penile-like appendages).

In short, most of the media reporting of this study has painted a much simpler story than there really is, and a closer look at the methods reveals that this study says very little about whether penis size is related to women’s pleasure. It seems that many journalists have an agenda to prove that “size matters,” but in their quest to do so, they have forgotten that it’s the facts that really matter.

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[3] Lippa, R. A. (2007). The preferred traits of mates in a cross-national study of heterosexual and homosexual men and women: An examination of biological and cultural influences. Archives Of Sexual Behavior, 36, 193-208.